题解 | 小红的01子序列构造（easy）

#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=2e5+10;

int n,k;
string s;


void solve(){
	
	int cnt0=0,cnt1=0;
	int l=0,r=0,sum=0;
	if(s[l]=='0') cnt0++;
	else cnt1++;
	
	while(l<n&&r<n){
		if(sum==k){
			cout<<l+1<<" "<<r+1<<endl;
			return;
		}else if(sum<k){
			r++;
			if(s[r]=='0'){
				cnt0++;
			}else{
				sum+=cnt0;
				cnt1++;
			}
		}else{
			if(s[l]=='0'){
				sum-=cnt1;
				cnt0--;
			}else{
				cnt1--;
			}
			l++; 
		}
	}
	cout<<-1<<endl;
	return;
}

signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	
	cin>>n>>k;
	cin>>s;
	
	solve();

    return 0;
}